List Chunk

Can now read List/Info chunks at the end of wav files. The general
trend seems to be putting them at the end of the file. Have made some
mini chunk objects too, could potentially make a 'List' class to make
things more thorough. Have just about managed to convert back into a
byte array. Encoding for list seems to be in UTF-8. There's a bunch of
crappy methods in HexByte I'm going to delete after this commit.